In a sentence
For decades his theory stood unassailed at the center of the field.
Synonyms
unchallengedundisputeduncontested
Antonyms
disputedchallengedcontested
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See all More GRE words starting with U
ubiquitous
seeming to be present everywhere at the same time
ululate
to howl or wail loudly, especially in grief or celebration
umbrage
offense or annoyance taken at a perceived slight
unalloyed
complete and unqualified, without anything to diminish it
unanimity
complete agreement among everyone involved
unassailable
impossible to attack, question, or refute
unassuming
modest and not seeking to draw attention to oneself
uncanny
strange or mysterious in an unsettling way
Learn words the way the GRE tests them.
Vocabulary sticks when you meet it in real sentences. Practise these words inside text completion and sentence equivalence questions.